There is known an electronic key system which includes at least one mobile device and an in-vehicle device mounted in a vehicle and which executes authentication processing based on a result of wireless information communication executed between the mobile device and the in-vehicle device (see patent literature 1).
In an electronic key system of the above type, a response request requesting mobile device identification information is transmitted from an in-vehicle device to a mobile device together with vehicle identification information. Such mobile device identification information is fixed-value identification information pre-allocated to each mobile device. The vehicle identification information also contains a fixed value pre-allocated to each vehicle to identify the vehicle.
When the mobile device receives the response request, the mobile device responds by transmitting the mobile device identification information allocated to the mobile device itself at a response timing. The response timing is registered in the mobile device. When the in-vehicle device receives the response, the in-vehicle device compares, for authentication, the received mobile device identification information with the mobile device identification information registered in the in-vehicle device. When the authentication is successful, the in-vehicle device unlocks/locks doors and/or starts up the internal combustion engine of the vehicle.
In such an electronic key system, the mobile device and the in-vehicle device execute information registration processing to register information required for the authentication processing in the mobile device and the in-vehicle device. Every time when the information registration processing is executed, the mobile device identification information on the mobile device is registered in the in-vehicle device, and the vehicle identification information and the response timing for the mobile device are registered in the mobile device.
Normally, when a user of the electronic key system executes information processing once, the user registers the vehicle identification information and the response timing in every desired mobile device in order to enable the electronic key system to function. The response timings registered in the desired mobile devices each time the information registration processing is executed are determined as unique ones on a mobile device by mobile device basis.
The inventor of the present application has found the following regarding electronic key systems.
In an electronic key system, there are cases where it becomes necessary to make a new mobile device function as an electronic key. In such cases, for the new mobile device with neither vehicle identification information nor registered response timing, it is necessary to newly register the vehicle identification information and response timing in the new mobile device.
In an existing type of electronic key system, it is possible by executing information registration processing to register the vehicle identification information and response timing in each mobile device and to register mobile device identification information in an in-vehicle device. However, in the information registration processing executed in an existing type of electronic key system, nothing is done about the mobile device identification information already registered in the in-vehicle device or the vehicle identification information and the response timing already registered in the mobile devices.
For example, assume that a mobile device (hereinafter referred to as an “existing registered mobile device”) in which vehicle identification information and response timing are already registered is present and that the vehicle identification information and response timing have been newly registered in another mobile device (hereinafter referred to as a “newly registered mobile device”) which previously had no vehicle identification information and no response timing registered in it. In this case, the existing registered mobile device and the newly registered mobile device have the same vehicle identification information and response timing registered in them.
In the above case of an existing type of electronic key system, when a response request requesting mobile device identification information is transmitted from the in-vehicle device together with vehicle identification information, an interference possibly occurs in such a way that both the existing registered mobile device and the newly registered mobile device transmit their mobile device identification information (MOBILE DEVICE CODE “a” and MOBILE DEVICE CODE “b” in FIG. 19) at the same response timing as shown in FIG. 19. When such interference occurs in an existing type of electronic key system, the authentication processing cannot be properly executed.
Namely, in an existing type of electronic key system, the same information may be registered in a plurality of mobile devices.